In elevators with large conveying heights a device for providing compensation for the weight of a suspension means is usually provided. The suspension means is guided over a drive pulley which in turn is drivable by means of an elevator drive. An elevator cage is arranged at one end of the suspension means and a counterweight is arranged at the other end of the suspension means. The elevator cage and the counterweight are movable by way of the suspension means in opposite directions in an elevator shaft, wherein the elevator cage serves stories.
If the elevator cage is disposed at the top in the elevator shaft, the suspension means length and the weight of the suspension means on the counterweight side is large. If the elevator cage is disposed at the bottom of the elevator shaft, the suspension means length and the weight of the suspension means on the cage side is large. Provided as compensation for the weight displacement from the counterweight side to the cage side and conversely is a compensating means which is arranged at one end underneath at the elevator cage and at the other end underneath at the counterweight. If, for example, the suspension means length is large on the counterweight side the compensating means length is small on the counterweight side and large on the cage side. Balancing of or compensation for the weight displacement on the part of the suspension means is provided by the compensating means acting in opposite directions. Drive torque, braking moment and traction at the drive pulley can be optimized by the weight compensation.
However, the compensating means hanging at the elevator cage and at the counterweight is susceptible to oscillation, including in the case of elevator installations with large conveying heights, or through other influences such as, for example, air in the elevator shaft, earthquakes or building fluctuations. In the case of movement of the elevator cage and the counterweight the compensating means, for example an encased chain, can be excited into oscillation, wherein the deflection of the compensating means in the case of further travel of the elevator cage and the counterweight can be amplified. The deflection can be of such a magnitude that the compensating means whips against the shaft walls. In that case there is the risk that the compensating means can tangle with shaft fittings, for example fastening brackets for guide rails. If the compensating means is tangled on the counterweight side and the elevator cage moves upwardly and the counterweight downwardly then the compensating means can be additionally tensioned from the damage point to the elevator cage and can be loose from the damage point to the counterweight. Such damage can be dangerous for safe operation of the elevator installation. In the extreme case the compensating means can break and cause consequential damage.